Tell Time and Blink an LED on Your Wrist with WatchDuino

Is your hipster wrist having a hard time waiting for the debut of the iWatch? There’s a new open hardware/software project out that could help calm your nerves. The WatchDuino is exactly what it sounds like, an Arduino-based wrist watch.

The component list is short and inexpensive. The meat and potatoes consist of an ATMega328, crystal, Nokia LCD screen and LiPo battery. The USB-rechargeable battery lasts about a week before needing to be such. Besides presenting the Time and Date in both analog or digital formats (as you would expect) there is an alarm and timer. Additionally, there are 2 games, Pong and Snake. Any lack of features is made up for the fact that the software is open and can be modified and added to by the community. We’re sure the development of this watch will be quick and significant.

Confirming the coolness of this project is the fact that it won 1st place in the 2014 BIICODE Programming Competition. If the WatchDuino is right up your alley, the documentation can be found here. Go make one!

OK, I digress somewhat, but in a similar vein, I need a time/date for a car backup-camera display. The 7″ display has 2 video inputs, so one is spare and I am guessing they are H-264. The display has a button to switch between Input lines.
When not driving backwards, I’d like a time/date display on input-2. I have a raspi, but not the skill levels to do this, plus, the rapsi in the old truck is probably overkill. Anyone have some practical thoughts or links that might get me started on this project? Lowest cost possible of course.

H-264? I’d sooner guess they were just analogue NTSC. Why bother digital encoding / decoding across 10 feet of wire? NTSC would cope with a noisy signal much better than any digital video, there’s plenty enough bandwidth to run it through a coaxial cable, and it’s the default format for many cameras and screens anyway!

On the good side that makes adding a Raspberry Pi quite a bit easier. Failing that there’s lots of projects using Arduinos / Atmels to generate video, often simple B&W, in NTSC.

I suppose it could be PAL, since the “broadcast” is only across a piece of wire. As long as the camera matches the screen. But that’s not a big problem either.

Unless I’ve missed something. Why did you guess it was H-264? Are they just RCA-plug inputs? That’s usually just composite PAL / NTSC video.

More complex option, they used to make kits to superimpose graphics for time / date over an analogue video stream, so you could have the time / date on top of your video. For security cameras etc. There might even be a chip that does it. You’d need to synchronise the video signal for your text with the video signal from your camera, so the syncs are all at the same time. That’s called Genlocking, a common thing.

Yeahhh, I can pretty much guarantee they’re composite video. It’ll probably take both NTSC and PAL. I’ve got a similar product as well. (Which I got for R/C FPV use)

If you want text displays on a video feed, I’d recommend an ATMega328 and a Maxim MAX7456. For your specific project, there’s any number of great RTC/Calendar chips available from Maxim (And they offer free samples.) to provide the date/time.

You know, now that I think about it, you could make such an OSD give you the output of pretty much anything you could interface through an Arduino… You said this was for a rearview/backup camera? How about an ultrasonic or laser rangefinder? ;)

Anyway, I can’t give you much more help beyond pointing you in the right direction: The ‘minimosd’, a popular OSD board for FPV flight by DIYDrones uses that same ATMega/MAX7456 combo. (And it can display all sorts of readouts and instrumentation on the video feed, it’s a pretty robust solution!) So take a look at their project. https://code.google.com/p/arducam-osd/wiki/minimosd

First mod I would make to the design is to ditch the nokia display for one of those Made In China OLED displays that are everywhere. The 128×64 or whatever ones that you can usually either get in all white, or blue with a row’s worth of yellow at the top.

No battery management? Even using the internal ADC & Voltage Reference of the ATMEGA to check keep the circuit powered down would be good enough here.

I’d be scared of this thing chewing through Li-Po cells (putting them beyond the safe discharge voltage), but I doubt it’s an issue really; the solder monkey in me says that board won’t last a month under normal usage, and the frequent need to reprogram the time (I get about a seconds worth of drift / day on a hand-soldered DS1302 on a breadboard) is surely going to contribute to that failure mode!